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Old 03-27-2013, 09:20 PM   #1
ozkiwi
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86 SILVERADO what discs do I need?

The supplier cant tell which one I need to replace the worn front rotors on my truck.part no 5006 which are 11 7/8th
or 5032 which are 11 41/64.
Truck is not here so can't measure.
Also rear wheel cylinder either 2 inch or 2 3/4.
Can any one help ?

Vin:2gcec14h2g1170202
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Old 03-28-2013, 08:07 AM   #2
Keith Seymore
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Re: 86 SILVERADO what discs do I need?

Yes -

Here is the brake system release chart for an '87 ('86 should be the same).

Scan through there and see what you find.





Your truck would be the equivalent of an R10, and I believe you'll find front rotors are 11.86" (probably what they are calling 11 7/8 = 11.875).

Additionally, you said "rear wheel cylinders" but your choices do not make sense. I think you meant the width of the rear brake shoes, which you will find to be 2.75".

K
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Last edited by Keith Seymore; 03-28-2013 at 08:14 AM.
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Old 03-28-2013, 10:01 AM   #3
silvereagle07
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Re: 86 SILVERADO what discs do I need?

Measure the thickness of the rotor. It will be 1" or 1.25". Then measure the depth of the drum. It will be 2" or 2.75".
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Old 03-28-2013, 10:31 AM   #4
Keith Seymore
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Re: 86 SILVERADO what discs do I need?

Quote:
Originally Posted by silvereagle07 View Post
Measure the thickness of the rotor. It will be 1" or 1.25". Then measure the depth of the drum. It will be 2" or 2.75".
Quote:
Originally Posted by ozkiwi View Post
Truck is not here so can't measure.
You probably missed that detail by being on your phone.

Can you see the chart? It's what we used in order to release the parts to production.

K
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Old 03-28-2013, 12:21 PM   #5
silvereagle07
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Re: 86 SILVERADO what discs do I need?

Sorry Keith. I missed original info on the tiny phone screen.
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Old 03-28-2013, 12:30 PM   #6
Keith Seymore
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Re: 86 SILVERADO what discs do I need?

Quote:
Originally Posted by silvereagle07 View Post
Sorry Keith. I missed original info on the tiny phone screen.
Thought so.

What do you wanna bet Ozkiwi is sleeping right now? He'll probably see this when he gets up in a few hours....

(lol)

K
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Old 04-02-2013, 04:00 AM   #7
ozkiwi
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Re: 86 SILVERADO what discs do I need?

The brake option is J55 is that the same as JB5 ?
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Old 04-02-2013, 07:46 AM   #8
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Re: 86 SILVERADO what discs do I need?

J55 brakes use the same rear shoes as JB5 / JD5 (11 5/32" x 2 3/4").
J55 indicates it has the HD brake system. I googled the GM RPO codes and found these pages. http://www.marshu.com/images-website...-car-codes.pdf
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Old 04-02-2013, 09:27 AM   #9
Keith Seymore
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Re: 86 SILVERADO what discs do I need?

Quote:
Originally Posted by ozkiwi View Post
The brake option is J55 is that the same as JB5 ?
Yes.

K
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Old 04-02-2013, 09:29 AM   #10
Keith Seymore
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Re: 86 SILVERADO what discs do I need?

Quote:
Originally Posted by silvereagle07 View Post
I googled the GM RPO codes and found these pages. http://www.marshu.com/images-website...-car-codes.pdf
Be careful - RPO codes can change and/or be re-used over the course of the model years. It's best if you can find RPO information specific to trucks and ideally for the model year of interest.

K
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